Image capturing apparatus and method of controlling the apparatus

ABSTRACT

An image capturing apparatus and its control method for capturing a moving image. Plural movie capturing modes with different control parameters are set in accordance with an instruction from a user. One of selectable frame rates is selected in accordance with video output setting by the user. Moving image frames are generated based on the selected frame rate and a control parameter corresponding to the frame rate, and recorded as a moving image on a recording medium.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image capturing apparatus capable ofcapturing a moving image and its control method.

2. Description of the Related Art

In recent years, a digital camera that records image data obtained byconverting an image signal of an object obtained with a solid-stateimage sensor such as a CCD into a digital signal into a recordingmedium, which has a movie capturing function in addition to a generalstill image capturing function is known. It is known that when moviecapturing is performed with an image capturing apparatus using a CCD ora CMOS sensor under a fluorescent light driven with a commercial powersupply, brightness fluctuation occurs by frame and/or bright/darkhorizontal stripes occur in a frame. The brightness/darkness fluctuationis called flicker which can be reduced by controlling an electronicshutter at a shutter speed of n/100 sec (n is a natural number) withrespect to flicker of 50 Hz, and a shutter speed of n/120 sec withrespect to flicker of 60 Hz.

On the other hand, some digital cameras with the movie capturingfunction have a function of arbitrarily selecting a recording size of amovie and a frame rate and a function of changing to a full-screendisplay or an enlarged display. Further, for appreciation of recordedstill images and moving images, such digital camera has a function ofplayback display on an LCD monitor unit or the like of the camera, andfurther, appreciation on a TV monitor or the like can be performedthrough a video output terminal or an HDMI terminal. As the video outputmode in this case, the NTSC or PAL system is adopted in the respectiveregions in the world.

Japanese Patent No. 3823314 discloses extraction of a flicker componentupon flicker detection by detection by each of plural flicker detectionregions set in a vertical scanning direction and obtaining a differencebetween brightness data of continuous two regions, then measuring aninterval between the extracted flicker components and converting theinterval to a frequency. Further, Japanese Patent Laid-Open No.07-298112 discloses, in a moving image pickup system, freely changing aframe rate upon recording or through operation in accordance withpurpose.

In a movie capturing function enabling frame rate selection, it might bedifficult to perform flicker detection in control at a selected framerate. Upon image capturing under a fluorescent light connected to acommercial power supply, brightness/darkness horizontal stripes occur ina recorded moving image. Further, when a recorded moving image isplayback-displayed, it is desirable to playback-display the moving imageat a frame rate selected upon recording. However, upon appreciation ofthe moving image on a TV monitor or the like via a video output terminalor an HDMI terminal, it is necessary to perform output at apredetermined frame rate based on standards of the NTSC or PAL system.Accordingly, appreciation is performed at a display frame rate which isdifferent from that upon recording.

SUMMARY OF THE INVENTION

An aspect of the present invention is to eliminate the above-mentionedproblems with the conventional technology.

The present invention has as its object, to provide an image capturingapparatus and its control method for selection and control of imagesignal readout and a frame rate in accordance with operation mode suchas still image capturing, movie recording at an arbitrary frame rate, anenlarged display and the like.

According to an aspect of the present invention, there is provided animage capturing apparatus comprising: a photographing unit configured tocapture image of an object to generate an image signal; a modechangeover unit configured to change to one of a plurality of imagecapturing modes corresponding to different video systems; and a controlunit configured to perform control so as to perform flicker detectionbased on an image signal obtained by setting a control parameter fordetecting flicker and performing image capturing operation by thephotographing unit, and then set a control parameter corresponding tothe image capturing mode changed by the mode changeover unit and performthe image capturing operation by the photographing unit, wherein thecontrol parameter for detecting flicker is different from the controlparameters corresponding to the plurality of image capturing modes.

According to another aspect of the present invention, there is provideda control method for controlling an image capturing apparatuscomprising: capturing image of an object to generate an image signal;changing to one of a plurality of image capturing modes corresponding todifferent video systems; and controlling to perform flicker detectionbased on an image signal obtained by setting a control parameter fordetecting flicker and performing image capturing operation in thecapturing step, and then set a control parameter corresponding to theimage capturing mode changed in the changing step and perform the imagecapturing operation in the capturing step, wherein the control parameterfor detecting flicker is different from the control parameterscorresponding to the plurality of image capturing modes.

Further features and aspects of the present invention will becomeapparent from the following description of exemplary embodiments, withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate an embodiment of the inventionand, together with the description, serve to explain the principles ofthe invention.

FIG. 1 depicts a perspective view illustrating an outer appearance of adigital camera according to an embodiment of the present invention.

FIG. 2 is a block diagram describing a circuit diagram of the digitalcamera according to the embodiment;

FIG. 3 is a flowchart describing the flow of movie capturing processingwith the digital camera;

FIG. 4 is a timing chart describing the movie capturing with the digitalcamera;

FIG. 5 depicts a view describing a table showing the relation betweenset operation modes and control parameters;

FIG. 6 depicts a view illustrating a table describing the relationbetween video output settings and selectable frame rates in the digitalcamera; and

FIG. 7 depicts a view illustrating a table describing the relationbetween the video output settings and the frame rates in the digitalcamera.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will now be described hereinafterin detail, with reference to the accompanying drawings. It is to beunderstood that the following embodiment is not intended to limit theclaims of the present invention, and that not all of the combinations ofthe aspects that are described according to the following embodiment arenecessarily required with respect to the means to solve the problemsaccording to the present invention.

FIG. 1 depicts a perspective view of an outer appearance of a digitalcamera 100 according to an embodiment of the present invention.

In FIG. 1, an accessory shoe 110, an optical viewfinder 104, an AE(automatic exposure) lock button 112, an AF focus detection pointselection button 113, and a release button 114 for a capturing operationare provided in an upper part of the digital camera 100. Further, a dial411, a mode dial 60 and a display unit 409 are provided. The dial 411 isa device to, with other operation button(s), input a numeral value intothe camera, and to input various signals to for example change an imagecapturing mode. Further, the display unit 409 having a liquid crystaldisplay displays information on image capturing conditions and the likesuch as a shutter speed, an aperture value, image capturing modescorresponding to different video systems.

Further, an LCD monitor 417 to display an object image, a capturedimage, various setting screen images is provided on the rear surface ofthe camera main body. Further, a playback switch 66 to display acaptured image on the LCD monitor 417, a single shooting/continuousshooting switch 68, a cross switch 116, an SET button 117, a menu button124 and a power source switch 72 are provided.

The single shooting/continuous shooting switch 68 is used for, when therelease button 114 is depressed, setting a single shooting mode toperform image capturing for 1 frame and to set the camera into a standbystatus or a continuous shooting mode to continuously perform imagecapturing while the release button 114 is depressed. The cross switch116 has four buttons provided in upper, lower, left and right positionsand the SET button 117 provided in the central position. The crossswitch 116 is used by a user to designate selection and execution ofmenu items displayed on the LCD monitor 417, in the camera. The menubutton 124 is a button for display of a menu screen for various camerasettings on the LCD monitor 417. For example, to select and set an imagecapturing mode (mode changeover), the menu button 124 is depressed thenthe upper, lower, left and right buttons of the cross switch 116 areoperated so as to select a desired mode. Then, in a status where thedesired mode is selected, the SET button 117 is depressed, thereby thesetting is completed.

FIG. 2 is a block diagram describing a circuit diagram of the digitalcamera according to the present embodiment.

The digital camera according to the present embodiment has aphotographing lens 10, a shutter 12 having an aperture function, animage sensor 14 to convert an object optical image into an electricsignal (image signal), and an A/D converter 16 to convert an analogsignal output from the image sensor 14 into a digital signal. Further, atiming generator 18, which supplies a clock signal and a control signalto the image sensor 14, the A/D converter 16 and the D/A converter 26,is controlled by a memory controller 22 and a system controller 50. Animage capturing controller 210 includes these image sensor 14, the A/Dconverter 16, the timing generator 18 and the like. An image processor20 performs predetermined pixel interpolating processing and colorconversion processing on data from the A/D converter 16 or data from thememory controller 22. Further, the image processor 20 performspredetermined calculation processing using captured image data. Thesystem controller 50 performs TTL (through the lens) AF (automaticfocus) processing, AE (automatic exposure) processing and EF (pre-flash)processing to control an exposure controller 40 and a focus controller42 based on the result of calculation. Further, the image processor 20also performs predetermined calculation processing using captured imagedata and performs TTL AWB (automatic white balance) processing based onthe result of calculation.

The memory controller 22 controls the A/D converter 16, the timinggenerator 18, the image processor 20, an display memory 24, the D/Aconverter 26, a memory 30, and a codec 32. Data from the A/D converter16 is written via the image processor 20 and the memory controller 22,or data from the A/D converter 16 is directly written via the memorycontroller 22, into the display memory 24 or the memory 30. An imagedisplay unit 28, corresponding to the LCD monitor 417 in FIG. 1, is adisplay unit such as a TFT-LCD. Image data for display written in thedisplay memory 24 is displayed with the image display unit 28 via theD/A converter 26. By sequentially displaying captured image data usingthe image display unit 28, an electronic viewfinder function can berealized. Further, the image display unit 28 can be arbitrarily ON/OFFcontrolled in accordance with an instruction from the system controller50. When the display is turned OFF, electric consumption of the digitalcamera 100 can be greatly reduced.

The memory 30 which is used for storage of captured still images andmoving image data has a sufficient storage capacity for storing apredetermined number of still images and moving image data for apredetermined time period. With this arrangement, even upon continuousshooting to continuously capture plural still images and panoramicshooting, high-speed and a large amount of image data can be writteninto the memory 30. Further, upon movie capturing, the memory 30 is alsoused as a frame buffer for storage of images continuously written at apredetermined rate. Further, the memory 30 is also used as a work areafor the system controller 50. The codec 32 compresses or decompressesimage data by ADCT (Adaptive Discrete Cosine Transform) or the like,reads an image stored in the memory 30 and performs expansion processingand compresses data to be written into the memory 30.

The exposure controller 40 controls the shutter 12 having an aperturefunction. The exposure controller 40 also has a flash exposure controlfunction in cooperation with a flash 48. The focus controller 42controls focusing with the photographing lens 10. A zoom controller 44controls zooming with the photographing lens 10. A barrier controller 46controls the operation of a barrier 102. The flash 48 has a lightprojecting function as an AF fill light and a flash control function.The exposure controller 40 and the focus controller 42 are controlledusing the TTL metering. The system controller 50 controls the exposurecontroller 40 and the focus controller 42 based on the result ofcalculation with the image processor 20 with respect to captured imagedata.

The system controller 50, having a CPU 50 a such as a microcomputer,controls the entire digital camera 100. A memory 52 holds constantnumbers, variables, programs and the like for the operation of thesystem controller 50. A display unit 54, such as a speaker and adisplay, displays operation statuses and messages using characters,images, voice messages and the like in accordance with execution of aprogram by the system controller 50. The display unit 54, having acombination of for example a liquid crystal display or LED, a soundgenerator and the like, is provided in single or plural recognizablepositions around an operation unit of the digital camera 100. Further, apart of the functions of the display unit 54 is provided in the opticalviewfinder 104. Among display contents displayed on the display unit 54,contents displayed on a liquid crystal display or the like are a singleshooting/continuous shooting mode, a self timer, a compression rate, thenumber of recording pixels, the number of recorded images, an availableshooting number, a shutter speed, an aperture value, an exposurecompensation, a flash mode, a red-eye reduction mode, and a macro imagecapturing mode. Further, a buzzer setting, a clock battery display, abattery display, an error display, information using a plural digitnumber, a recording medium 200 attachment/detachment status, acommunication I/F operation, a date/time display and the like, areincluded. Further, among the display contents on the display unit 54, ascontents displayed in the optical viewfinder 104, an in-focusindication, a camera-shake warning display, a flash charging display, ashutter speed, an aperture value, an exposure correction and the likeare provided. As a nonvolatile memory 56, an electrically erasable andrecordable memory such as an EEPROM is used.

An operation mechanism (60, 62, 64 and 70) is a device which is a singleor a combination of plural devices such as switches, dials, a touchpanel, a device for positioning by detection of line of sight and adevice for speech recognition, to input various operation instructionsfor the system controller 50. A mode dial switch 60 is used for changingand setting from various function modes including a power off mode, anauto shooting mode, an image capturing mode, a panoramic shooting mode,a playback mode, a multi-frame playback/erase mode and a movie capturingmode. A shutter switch 62 (SW1) becomes ON in the middle of operation ofthe above-described release button 114, to instruct to start AF (autofocus) processing, AE (auto exposure) processing, AWB (auto whitebalance) processing, EF (pre-flash) processing or the like. A shutterswitch 64 (SW2) becomes ON upon completion of the operation of therelease button 114, to instruct to start exposure processing to write asignal read from the image sensor 14 via the A/D converter 16 and thememory controller 22 into the memory 30, and developing processing,further, to instruct to start the operation of recording processing toread image data from the memory 30, compress the image data with thecodec 32 and write the compressed data into the recording medium 200.

An operation unit 70 includes various buttons such as a live viewstart/stop button, a movie recording start/stop button, a menu button, aset button, a macro button, a new page button and a flash settingbutton, a touch panel, and the like. Further, the operation unit 70includes a single/continuous/self-timer set button, a menu movement +(plus) button, a menu movement − (minus) button, a playback imagemovement + (plus) button, a playback image movement − (minus) button, acapturing image quality selection button, an exposure compensationbutton and a date/time setting button. That is, the playback switch 66,the single shooting/continuous shooting switch 68, the cross switch 116,the SET button 117, the menu button 124 and the like shown in FIG. 1 areincluded.

A GPS antenna 74 receives an electric wave from a GPS satellite. A GPSunit 76 performs calculation from the received data, and detects acurrent position. Map information stored in the nonvolatile memory 56 orthe memory 30 can be read, or map information from an external devicecan be read through an interface 90 or a communication unit 110, basedon the positional information. Further, a timer unit 78 holds currenttime information (year/month/day, time/minute/second and day of week).

A power supply controller 80 has a battery detection circuit, a DC-DCconverter, a switch circuit for change of energized block and the like.The power supply controller 80 detects a battery attached/detachedstatus, a battery type and a battery remaining capacity, then controlsthe DC-DC converter based on the result of detection and an instructionfrom the system controller 50, and supplies necessary voltage to therespective units including the recording medium for a necessary period.Reference numerals 82 and 84 denote connectors. An electric power source86 is a primary battery such as an alkali battery or a lithium battery,or a secondary battery such as an NiCd battery, an NiMH battery or an Libattery, or an AC adapter, or the like.

The interface 90 is an interface with respect to a recording medium suchas a memory card, a hard disk or the like. A connector 92 is connectedto the recording medium such as a memory card or a hard disk. Note thatin the present embodiment, the apparatus has an interface and aconnector for attachment of a recording medium. The interface and theconnector for attachment of the recording medium may be provided in asingle or plural positions. Further, a removable or nonremovable mediummay be used as the recording medium.

Further, a combination of an interface and a connector based ondifferent standards may be provided. An interface and a connectorcompliant with PCMCIA card or CF (compact flash) card standards may beused. Further, the interface 90 and the connector 92 compliant with thePCMCIA card or CF (compact flash) card standards may be employed.Various communication cards such as a LAN card, a modem card, a USBcard, an IEEE1394 card, a P1284 card, a SCSI card and a PHS card may beconnected. With this arrangement, image data and management informationattached to the image data can be transmitted/received with respect to aperipheral device such as another computer or a printer.

An interface 94 and a connector 96 are connection terminals forconnection of cables connected to a television monitor 214, which arecomponent output and HDMI output terminals and the like compliant withTV standards. In accordance with setting status or cable connectionstatus, the LCD monitor 417 or the television monitor 214 can beselected as a display output destination, otherwise, display output canbe simultaneously performed on these monitors.

The barrier 102 covers an image capturing part of the digital camera 100including the lens 10, to prevent soil and/or breakage of an imagecapturing unit. The optical viewfinder 104 is capable of image capturingonly using an optical finder without the electronic viewfinder functionwith the image display unit 28. Further, a part of the functions of thedisplay unit 54, for example an in-focus indication, a camera-shakewarning display, a flash charging display, a shutter speed display, anaperture value display, an exposure compensation display and the likeare provided in the optical viewfinder 104.

A communication unit 110 is capable of communication with anotherexternal device by at least RS232C, USB, IEEE1394, P1284, SCSI, modem orLAN communication, or radio communication via an antenna 115. With thisarrangement, image data and/or management information attached to theimage data can be transmitted/received with respect to an externaldevice such as another computer or a printer via the communication unit110.

A recording medium 200 has a storage unit 202 such as a semiconductormemory or a magnetic disc, an interface 204 between the recording mediumand the digital camera 100, and a connector 206 for connection to thedigital camera 100. The recording medium 200 is for example a memorycard or a hard disk.

FIG. 3 is a flowchart describing movie capturing processing with thedigital camera 100 according to the present embodiment. This processingis performed by execution of the program stored in the nonvolatilememory 56 by the CPU 50 a of the system controller 50.

FIG. 4 is a timing chart describing the movie capturing with the digitalcamera 100 according to the present embodiment. Next, the moviecapturing processing with the digital camera 100 according to thepresent embodiment will be described using FIGS. 3 and 4.

To perform movie capturing, first, it is necessary to use the menubutton 124 and the mode dial 60 to change the image capturing mode fromthe still image capturing mode to the movie capturing mode. When theimage capturing mode is changed to the movie capturing mode, the systemcontroller 50 moves a quick return mirror (not shown) to the outside aphotographic optical path, and releases the shutter 12 to expose theimage sensor 14 to object light. At this time, image data read from theimage sensor 14 is continuously written at a frame period denoted bynumeral 401 in FIG. 4 into the memory 30 which functions as a framebuffer as denoted by numeral 402.

The processing in FIG. 3 is started in accordance with instruction ofthe movie capturing mode. First, in step S1, flicker detection isperformed for a constant period after the instruction of the moviecapturing mode. That is, the presence/absence of flicker and thefrequency are detected based on the image signal output from the imagesensor 14 by controlling the readout of the image signal output from theimage sensor 14 and the frame period using a flicker detection controlparameter to be described later. When the flicker detection has beencompleted, the process proceeds to step S2, in which image capturingcontrol changeover processing is performed in correspondence with thepreviously-set image capturing mode, the setting of the moving imageframe rate, the full-screen display or enlarged display.

Next, the process proceeds to step S3, in which the LCD monitor 417 iscaused to function as an electronic viewfinder (EVF). Then, the movingimage data written in the memory 30 (frame buffer) is read using theimage processor 20 and various image processings are performed inaccordance with necessity, and the processed image data is displayed onthe LCD monitor 417. In step S4, when the image capturing mode and/orthe moving image frame rate are changed and/or the screen display ischanged to full-screen/enlarged display using the menu button 124 and/orthe mode dial 60, image capturing control changeover processing isperformed in correspondence with the changed contents.

In step S5, when turning ON of the movie recording start button of theoperation unit 70 (for example, depression of the SET button 117 in themovie capturing mode) is detected, the process proceeds to step S6. Instep S6, the movie capturing processing to record a captured movingimage in the operation mode, set with the operation mode changeoverprocessing in step S2 or S4, is started. When the movie capturingprocessing is started, then in step S7, the image data written in theframe buffer is read, the image data is compressed using the codec 32,and a moving image frame is generated as denoted by numeral 403 in FIG.4. Then, the process proceeds to step S8, in which the moving imageframe is written into the recording medium 200. Then in step S9, it isdetermined whether or not termination of movie capturing has beeninstructed. When it is determined that the termination of moviecapturing has not instructed, the process returns to step S6 tocontinuously perform the movie recording processing.

FIG. 5 depicts a view illustrating a table describing the relationbetween the operation modes set in the image capturing controlchangeover processing in step S2 or S4 in FIG. 3 and control parameters.

First, as frame rate types according to the present embodiment, 22, 24,25, 30, 50 and 60 fps are prepared. Note that 22 fps is used for flickerdetection as a predetermined frame rate not in synchronization withflicker in the commercial power supply frequencies of 50 Hz and 60 Hz.The other 24, 25, 30, 50 and 60 fps are user-selectable moving imageframe rates. In this manner, the control parameter is used fordesignation of the recording frame rate in still image capturing and/ormovie capturing and image signal readout such as thinning reading withthe image capturing device.

Further, as the readout with the image sensor 14 according to thepresent embodiment, “full-pixel readout”, “thinning readout 1”,“thinning readout 2”, and “partial readout” are employed. The“full-pixel readout” is a mode to read image data detected with all thepixels of the image sensor 14 in vertical and horizontal directions usedonly upon still image capturing since the period of reading is long. The“thinning readout 1” is a mode for high speed reading with the ⅓ of allthe pixels of the image sensor 14 used upon EVF display in normal stillimage capturing or recording at 24, 25 or 30 fps moving image framerate. Further, the “thinning readout 2” is a mode for higher speedreading with increased thinning ratio in comparison with the “thinningreadout 1” at 50 or 60 fps moving image frame rate. The “partialreadout” is set when only a part of image data of angle of view is usedupon for example enlarged display by reading only pixel data detected ina part of the area of the image sensor 14 without thinning.

As described above, in the image capturing control changeover processingin step S2 or S4 in FIG. 3, the readout with the image sensor and theframe rate shown in FIG. 5 are determined in accordance with setoperation status, and the image capturing control is changed.

FIG. 6 depicts a view illustrating a table describing the relationbetween video output settings and selectable frame rates in the digitalcamera 100 according to the present embodiment. The relation betweenvideo output settings and selectable frame rates is stored as a table infor example the nonvolatile memory 56. When the video output mode isset, selectable frame rates are displayed on the LCD monitor 417 incorrespondence with the set video output mode for the user's selection.This operation is performed at step S4 in the above-described FIG. 3.

When the video output setting is the NTSC system as one of televisionbroadcast standards, the display frame rate is 60 fps. Accordingly, forsynchronization with the display frame rate, 30 and 60 fps to satisfy 60fps/n (integer) are selectable. On the other hand, when the video outputsetting is the PAL system as another television broadcast standard, thedisplay frame rate is 50 fps. Accordingly, for synchronization with thedisplay frame rate, 25 and 50 fps to satisfy 50 fps/n (integer) areselectable. Further, as the frame rate of 24 fps corresponding to a filmmode (cinema mode) is not in complete synchronization with any of thevideo output settings, this frame rate is selectable in both NTSC andPAL systems.

FIG. 7 depicts a view illustrating a table describing the relationbetween the video output settings and the frame rates automaticallyselected as a default setting (initial setting) upon video outputsetting changeover in the digital camera 100 according to the presentembodiment.

In a case where the frame rate of 30 fps is selected in the NTSC system,when the video output setting is changed to the PAL system, the framerate of 25 fps is automatically selected as shown in FIG. 7. On theother hand, in a case where the frame rate of 25 fps is selected in thePAL system, when the video output setting is changed to the NTSC system,the frame rate of 30 fps is automatically selected. Further, in a casewhere the frame rate of 60 fps is selected in the NTSC system, when thevideo output setting is changed to the PAL system, the frame rate of 50fps is automatically selected. On the other hand, in a case where theframe rate of 50 fps is selected in the PAL system, when the videooutput setting is changed to the NTSC system, the frame rate of 60 fpsis automatically selected.

As described above, according to the present embodiment, control isperformed such that image data readout from the image sensor and arecording frame rate can be selected in accordance with image capturingoperation status such as still image capturing, movie capturing andrecording at an arbitrary frame rate or enlarged display. With thisarrangement, optimum EVF display and movie recording can be realized ineach operation status. Further, image quality degradation due to flickerin displayed images and recorded images can be prevented by flickerdetection control before EVF display in the movie capturing mode orduring a first constant time period after the start of the moviecapturing mode. Further, as a captured moving image is not EVF displayedduring flicker detection, unnatural moving image display can beprevented. Further, unconformity between a selected moving image framerate and a video display frame rate can be prevented by setting movingimage frame rates which can be selected in accordance with video outputsetting.

As described above, the embodiment of the present invention has beendescribed, however, the present invention is not limited to theabove-described embodiment, but various modifications and changes can bemade within the scope of the object matter. For example, in the presentembodiment, as enlarged display cannot be performed with the assumedspecifications upon movie recording, the frame rate of 30 fps is fixedupon the enlarged display. However, if the specifications are arrangedsuch that movie recording can be performed while enlarged display isperformed, otherwise if enlarged display can be performed during movierecording in the specifications, the frame rate can be changed to a setframe rate and movie recording can be performed.

Aspects of the present invention can also be realized by a computer of asystem or apparatus (or devices such as a CPU or MPU) that reads out andexecutes a program recorded on a memory device to perform the functionsof the above-described embodiment(s), and by a method, the steps ofwhich are performed by a computer of a system or apparatus by, forexample, reading out and executing a program recorded on a memory deviceto perform the functions of the above-described embodiment(s). For thispurpose, the program is provided to the computer for example via anetwork or from a recording medium of various types serving as thememory device (for example, computer-readable medium).

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2009-194642, filed Aug. 25, 2009, which is hereby incorporated byreference herein in its entirety.

1. An image capturing apparatus comprising: a photographing unitconfigured to capture image of an object to generate an image signal; amode changeover unit configured to change to one of a plurality of imagecapturing modes corresponding to different video systems; and a controlunit configured to perform control so as to perform flicker detectionbased on an image signal obtained by setting a control parameter fordetecting flicker and performing image capturing operation by thephotographing unit, and then set a control parameter corresponding tothe image capturing mode changed by the mode changeover unit and performthe image capturing operation by the photographing unit, wherein thecontrol parameter for detecting flicker is different from the controlparameters corresponding to the plurality of image capturing modes. 2.The image capturing apparatus according to claim 1, wherein the controlparameter specifies a frame rate for the image signal.
 3. The imagecapturing apparatus according to claim 1, wherein the control parameterspecifies a method of reading out the image signal from thephotographing unit.
 4. The image capturing apparatus according to claim2, further comprising a recording unit configured to record the imagesignal at a frame rate specified by the control parameter on a recordingmedium.
 5. The image capturing apparatus according to claim 1, whereinthe frame rate specified by the control parameter for detecting flickeris a frame rate not in synchronization with a frequency of a commercialpower supply.
 6. A control method for controlling an image capturingapparatus comprising: capturing image of an object to generate an imagesignal; changing to one of a plurality of image capturing modescorresponding to different video systems; and controlling to performflicker detection based on an image signal obtained by setting a controlparameter for detecting flicker and performing image capturing operationin the capturing step, and then set a control parameter corresponding tothe image capturing mode changed in the changing step and perform theimage capturing operation in the capturing step, wherein the controlparameter for detecting flicker is different from the control parameterscorresponding to the plurality of image capturing modes.